Terminal for bushings



"A, o. Aus-rm TERMINAL FOR BUSHINGS 2 sheets-sheet 1 nieu July ze. lsz

3 'In I ATTORNEY Nov. 13, 1,928.

A.- Aus-HN TERMINAL FOR BUSHINGS Filed July 29. 1922 2 sheets-sheet 2 A TTORNE Y Patented Nov. 13, `1928.

UNITED STATES .ARTHUR O. AUSTIN, OF BARBER/TON,

1,691,327 PATENT oFFicE.

OHIO, ASSIGNOR, BY MESNE-ASSIGNMENTS, TO

THE OHIO :BRASS COMPANY, F MANSFIELD, OHIO, A CORPORATION OF NEW JERSEY.

Application filed July 29,

This invention relates to bushing insulators for transformer casings or other constructions in whicha conductor passes thru a portion of they constructionfrom which it is n to be electrically insulated, and it has for its object, the provision of'construction which permits the removal or installation of the bushing without lowering the oil level in the transformer casing or other similar device, and permits all connections to be made on the outside of the transformer, switch, or other device upon which the bushing is used.' Another object is to provide a bushing insula tor which shall be `of improved construction, efficient in operation, and which shall be con venient to install and replace. In the drawing: Fig. 1 is a part elevation and part section, showing one form of the invention. Fig. 2 is a fragmentary view showing a modiied form of a portion of the invention. Fig. 3 is a viewsimilar to Fig. 1 showing a modification of the invention.

Figs. 4 and 5 are fragmentary sections p showing modified. forms of connections for the lower end of the terminal rod in Fig. 3.

The improvement includes means vfor drawing the lead up holding same in plac while the weather cap is being tightened. n order to accomplish y the desired result "with certainty, it is necessary to provide means for preventing rota, tion .of the center rod and a gasket is also necessary for making an air tight joint.

In the particular form shown in Fig. 1, the conductor 10 -running thru the^bushing is usedfto provi-dethe necessary force for holding the weather cap 11 in place, and also for providing force between the upper lend 12 of the conductor 10 and the terminal cap 11 to insure good electrical contact. Rotation of the conductor 10 may beprevented by projections or an angular shank 13 on the rod and fitting loosely in a bushing 14 secured in the upper end of the opening 15 in the dielectric member 16. To insure tightness, all that isnecessary is to insert a gasket 17 and screw the cap terminal 11 down on rod 10 until the washer 18 is drawn up against Athe bottomof the bushing. This washer may be an ordinary washer, or it may be in the form cfa spring washer so that the contraction and exansion of the conductor 10 with the change 1n temperature of the transformer will not thru the bushing and TERMINAL FOB BUSHINGS.

1922. Serial N0. 578.464,.

eiect the tightness of the gasket 17.. The washer 18 may be provided with ridges or teeth 19 formed thereon to engage notches in the lower endfof the bushing 16 to prevent rotation of the washer. The nut 20 is secured to the rod 10 by pin 21 and engages stops 22 on the washer' 18 to hold the rod 10 from rotation. This arrangement may be used in conjunction with the angular portion l 13 or either may be used independently of one another.

Vhere the current is small and a spring lwasher is used, it is possible to use a conof the spring washer is not so necessary.

It sometimes happens, however, where a long bushing is used and there is considerable expansion in the conductor owing to an increase in temperature that the expansion in this conductor will reduce the pressure on the gasket and permit a leak. This reduction in the pressure may also permit an increase in the contact resistance between the conductor and the terminal cap. It is seen that by providing the necessary spring in the washer that this difficulty may be overcome and all stresses on the bushing under normal conditions will be in compression.

The length of the bushin frequently varies slightly, and it is advisabe to compensate for this change in length. "This may be accomplished by adjusting the nut 2O below the washer 18. The nut may be prevented from turning by pinning as by pin 21 or brazing to the rod 10. Where the rod 10, nut

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vhas projecting ribs 26 which engage corre-l sponding grooves in the insulating member.

The arrangement shown provides means for holding the lower end of the conductor 23 so that tension may be applied to same.v The construction further provides that this washer or the conducting rod will be prevented from rotation so that the terminal cap 11 may be tightened. With the form shown, the washers at the lower end of the bushing preferably do not lmake a tight joint. This permits the free expansion of the oil or insulating compound between the conductor 10 and the wall of the bushing. This forni of construction also permits the additional insulation of the oil lilm between the conductorlO and the walls of the bushing. In order to insure the filling of this space, it is sometimes necessary to allow the air to escape by loosening the terminal cap 11 and then retighten. The screw cap 27 provides means for removing the outside connections so that the terminal cap 11 may be tightened or loosened without interference. Where it is not necessary to provide an4 air or oil tight joint in the bushing, the gasket 17 may be removed or may consist of material which will simply forma cushion between the porcelain and metal.

The improved form of terminal shown in Fig. 3 provides means for removing or replacing a bushing in a transformer or other device without disturbing any connections other than those at the top ofthe bushing. Means are also provided for making an air vor oil tight joint at the bottom of the bushing.

With the improvement as shown, it is not necessary .in the tightening operation for the members in contact with the gasket to rot-ate with respect to the gasket. Thisv permits tightening moreeasily, and there is not so much danger of breaking the gasket.

In the device shown, the locking Harige washer 28 is threaded tightly on to the condiictor 29. During installation, the conductor 29 is drawn up thru the bushing by a wire attached to the eye 30 in the upper end of the conductor. The nut 31 is then screwed down far enough .so as to hold the conductor 29 from dropping back. A spring washer 32 or a gasket is then placed between the top of the bushing and the weather cap 33. The weather cap 33 is then tightened by screwing down on the thread 34 until the locking washer y28 at the lower end is drawn up tightly against the bushing or against the gasket 35. The center rod 29 is prevented from rotation by the pin 36 locking it to the locking washer 28. The locking washer in turn is prevented from rotation by 'lugs or projections 37 which engage in corresponding recesses in the bushing. By providing several holes 38 in the rod, it is possible to make adjustment to coinpensate for different lengthbushings.

Where an air or oil tight joint is necessary, a ltight fit must be insured between the locking washer 28 and the conductor 29 on which it is threaded. rIhis type of terminal has the advantage, that any pressure within will tend to increase the pressure on the joint and keep the same'tight.

Figure 4 shows-a slightly different form of lower connection. In this instance, rotation is prevented by the tapered angular section of the nut 39 engaging a corresponding recess in the bushing. Rotation between the locking washer and conductor may be prevented by means of a lock nut 40 or by any other suitable means. If a suiciently tight fit is secured between the locking washers and the conductor, no other locking means is necessary. In Fig. 4 no gasket is shown between the lower end of the bushing and the locking washer. 1 It is evident, however, that a tight joint may be insured by the use of a suitable gasket.

In Figure 5 a slightly different form is shown where the gasket is inside the locking lugs. The locking washer 41 having projecting lugs 42 ris formed by upsetting the conductor 43 or by brazing a suitable piece to saine. As the gasket 44 may be quite small in this case, a comparatively hard gasket may be used such as a copper or lead gasket or a copper gasket filled with asbestos or any other suitable form.

The portion 45 of the bushing projecting below the flange 41 tends to increase the insulation to ground and also tends to prevent electrical discharge from the flange 41 and projections 42.

This type of terminal is particularly suited* to conditions wherea rod or tubular conductor is used in the bushing, and also where it is desired to furnish a fixed position for the lead at the lowerend. After leaving the bushing the conductor rod may be bent so as to provide clearance for the attached leadas well as support so that it will not become mis laced and cause breakdown below the sur ace of the oil.l

I claim:

l. In combination a dielectric bushing', a conductor extending thru an opening in said bushing, a holding member connected with said conductor at one end of said bushing. a terminal member having threaded connection with said conductor at the gpposite end no er for takof said bushing, and a lspring w assise? ing up longitudinal play between said conductor and bushing said spring washer having means thereon co-operating with said conductor and bushing for preventing rotation ot said conductor in said busl'iing.' t

2. In combination a dielectric bushing, a conductor rod extending thru said bushing, means connected with said rod for engaging the inner end of' said bushing for limiting the outward movement of said rod, means removably connected with the outer end of said rod for holding the end of said rod against movement into said bushing, means for preventing rotation ot said rod in said bushing,

- anda closure member threaded onto said rod at the outer end thereof and having a bearing portion registering with said bushing and exerting an outward tension on said rod.

3. In combination a dielectric bushing, a

conductor rod extending thru said bushing,y

means for limiting outward movement of said rod7 a nut threaded on the outer end ot said rod, a weather cap threaded on the outer end of said rod independently of said nut, and having a bearing portion registering with said bushing and a spring washer interacting between said conductor rod and bushing so that said weather cap when tightened exerts pressure on said washer.

4. In combination a dielectric bushing having an angular shaped opening, a conductor rod extending thru said bushing and having an angular shaped portion disposed in said opening to prevent rotation thereof relative to said bushing, a stop connected with the inner end of said rod lfor limiting the outward movement thereof, means for holding said rod against retraction into said bushing and an impertorate cap threaded on the outer end of said rod and having a bearing portion registering with said bushing for closing the opening thru said bushing, the threaded connection between said cap and rod exerting outward tension on said rod to press said cap toward said bushing and to insure good electrical contact between said cap and rod.

5. In combination a dielectric bushing, a conductor rod extending thru said bushing, a stop at the inner end of said rod for l1miting outward movement thereof, a spring washer interposed between said stop and bushing, and means on said washer co-operating with said conductor and bushing for preventing rotation of said rod relative to said bushing. l

6. In combination a dielectric bushing having an angular shaped opening, a conductor rod extending thru said bushing, a stop on the inner end of said rod for limiting outward movement thereof, a terminal member threaded on the outer end of said rodsaid `rod having an angular portion thereon distween said stop and said dielectric member and supplementary means on said washer cooperating with said rod and bushing for resisting rotation `ot said rod.

Y. In combination an elongated tubular dielectric bushing having an angular shaped opening, a conductor rod extending thru said bushing and having an angular portion thereon tor preventing rotation relative to said bushing, a stop adjustably connected with the inner end of said rod for limiting outward movement thereof, a spring washer interposed Vbetween said stop and the inner'end of ysaid bushing, a nut threaded on the outer end of said rod for preventing retraction ot said rod in said bushing, an impertorate weather cap threaded on the outer end oi said rod independently of said nut, and a gasket interposed between said weather cap and the end of said bushing.

8. In combination, a dielectric bushing, a conductor rod extending through said bushing, a stop connected with said rod for limiting the outward movement of said rod, a nut threaded on the outer end of said rod, a-

weather cap threaded on the outer end of said rod independently of said nut and having a bearing portion registering with said bushing, and a spring washer interacting between said conductor rod and bushing so that said Weather cap when tightened exerts pressure onsaidwasher. e

' 9. In combination, a dielectric bushing having an angular'shaped opening, a conductor rod extending through said bushing and having an angular shaped portion disposed in said opening to preventrotation thereof relative to said bushing, a stop connected with the inner end of said rod for limiting the' outward movement thereof, a stop removably secured to the outer end of said rod for holding said rod against retraction into said bushing, and an imperforate cap threaded on the outer .end of said rod and having a bearing portion registering with said bushing for closing the opening through said bushing, the threaded connection between said cap and rod being arranged to exert outward tension on said rod to press said cap toward said bushing ,and to insure good electrical contact between said cap and rod.

Intestimony whereof I have signed my name to this specification on this 25th day oitv 

